Lap seam for coated cord fabric and method of making same



Oct. 28, 1952 M. M. CUNNINGHAM LAP SEAM FOR COATED CORD FABRIC AND METHOD OF MAKING SAME Filed Oct. 20, 1949 IN V EN TOR.

ATTORNEY seam.

Patented Oct. 28, 1952 11UN1TEosTATEs JoFFlcE LAI SEAM FOR COATED CORDv FABRIC AND METHOD OF MAKING SAME Marion M. Cunningham, Woonsocket, R. I., as-

sgnor to United States Rubber Company, New York, N. Y., a corporation ofvNew Jersey Application October 20, 1949, Serial No. 122,460

2 claims. (o1. 15o-'05) VThis invention relates to an improved nonwicking lap seam for coated cord fabric and a method of forming the same. f

It has been the practice heretofore to manu'- facture liquid containers for fuel, Water, chemicals, etc., from multi-ply layers of cord fabric coated with rubber, synthetic rubber or other suitable plastic composition resistant to the contents of the container. The inner liner ply of these containers must be entirely leakproof. The sheets of cord fabric forming a container or at least the cord fabric sheet used to form the inner liner of the container is preferably provided with lapv seams because of the added strength, but such lap seams have an edge exposed to the contents of the container. This exposed edge frequently permits the container contents to reach the reinforcing cords of the fabric, with the result that such cords absorb the liquid of the containers, and by wicking action transfer cords of the next layer, to thereby form a strong container wall which is subsequently cured or vulcanized if the cord fabric is formed of vulcanizable coating material, so as to bond the plies together. Cord fabric such as herein contemplated hasstrength in only one direction., the

the liquid through the fabric. Saturation of the cord fabric in this way causes an increase in thev weight of the container, and in some cases isresponsible for the delamination of the fabric plies forming the inner container wall.

To prevent the confined liquid from coming in contact with the exposed reinforcing cords along the edge of the seam, it has been customary heretofore to seal over this fabric seam, which extends parallel to the cords, by covering it with a strip of gum tape made from the same material as the coating composition of the cord fabric. This tape is bonded to theexposed surface of the cord fabric at eachside of the over-lapped seam, but it is found diicult to bond this tape so firmly in place that no leakage will occur whichf'will allow the liquidkto contact one or more cords of the cord,I fabric.

The vpresent invention obviates the use of such gum strips over these lap seams and provides a simple construction for forming a liquid tight In carrying out the present invention two marginal portions of the cord fabric are overlapped, but before theseoverlapped portions are bonded together, one or more cords is stripped from the outer marginal sheet to leave a lip of rubber or other coating material projecting befiller strands when used are extremely weak and are incorporated only to facilitate handling the cords during processing. Such cord fabric obviously cannot be used in asingle ply form because it possesses strength in only one direction, and 'at least two plies should be used with the cords of one ply extending at a pronounced angle to the cords of the adjacent plies. To compensate for the 'uni-directional strength, it is the general practice to build up and bond together successive layers in angular relation, and the laminated wall thus produced has strength in all directions.

The lap seam of the present invention is designed more especially for use on the inner ply' of such a laminated container wall, because only the inner ply comes in contact with the contents of the container and is required to be leak-proof, butsuch lap seam may be used for other plies.

The details of the present invention will be further understood by referring to the accompanying drawing, in which;

Fig. 1 is a perspective view of a coated cord fabric tank shown built upon a supporting form;

Fig. 2, lon a larger scale, is a sectional perspective. view showing an intermediate step in forming the lap seam of the tank of Fig. 1;

Fig."3 is an enlarged sectional view taken on the line 3-3 of Fig. l; and

Fig. 4 isv a'v'ievv similar to Fig. 3 showing jthe appearance of the seamy after the tank has been removed from thefo'rm and turned to place the lining at the inner face of the tank.

Fig. 1 shows a flexible tank or container which is or may be of conventional construction, except for the lapped seam I0. This tank is shown as built up upon a form II made of any relatively rigid material that will support the plies of coated cord fabricthat are laid thereupon in building the container. This container is shown as formed of one ply I2 of cord fabric having the cords I3 extending horizontally orcircumferentially about :the form I I, and a second ply I4 having the cords I5 extending vertically or axially of the form. The bottom of this tank is shown as formed of the ply sheets I6 and Il and the outer marginal portions of these sheets I6 and Il overlap and are bonded to the lower end portions of the side wall plies I2 and I4.

The tank shown in Fig. 1 is built inside out upon the form Ii, as this gives the tank the desired shape and also gives the workmen building the tank a better opportunity firmly to seal the fabric joints at the surface of the tank lwhich will later contact the confined liquid, when the tank is in use. The tank shown in Fig. 1, it is assumed, has been completed and vulcanized on the form I I, all that remains is to remove it from this form and turn it inside out, so that the lapped seam I!) which appears at the outer face of the tank in Figs. l, 2 and 3 will appear at the inner face of the tank, as shown in Fig. 4, when the form II has been removed and the tank is turned inside out.

Now referring more particularly to Fig. 2 of the drawing, the curved side wall of the form is indicated by the numeral I I, and in direct contact with the outer curved surface of this wall I I liesA the cord fabric l2 having the horizontally extending cords I3. Over the cord fabric I2 is provided the second cord fabric I4 having the vertically extending cords I5. Both cord fabrics I2 and I4 may be of similar construction and each is formed of parallel textile cords that are embeddedV in a sheet of rubber, rubber-like material, or plastic material, and it should be noted that the rubberlike material in each of the cord fabrics I2 and I4 is thicker at one face of the cords than'at the other. This is desirable in respect to the cord fabric i4, which is to form the inner lining when the tank is finished, so as to provide a relatively thick layer of rubber between the contents of the tank and the cords I5. Such a construction is also desirable for the outer cord fabric I2 in the finished tank so that the thick-rubber iilm at the outer face of the tank will protect the cords i3l from injury.

In building the tank or container shown in Fig. 1 of the drawing unvulcanized cord fabric, such as tire cord fabric may be used, and the rst cord fabric ply is laid upon the form I i, as above stated, with the cords extending horizontally in the'construction shown. The second ply is then laid over the first in the construction shown so that the cords i5 extend vertically, and the lapped seam I is formed by laying the outer marginal portion i8 of this cord fabric i4 over the inner marginal portion I9 as best shown in Fig. 2'. Then, in accordance with the present invention, one, two or more cords I5 are Yremoved adjacent the outer edge of this marginal portion I8 to leave a cord free lip 20 yas shown in Fig. 2. Next this overlapping portion I8 is rolled or pressed down into nrm engagement with the face ofthe portion I9 it overlaps, so that the lip 2U vwill be firmly bonded to the underlying surface as shown in Fig. 3 and preventsl the liquid which will later contact the inner wall of the tank from entering this seam or reaching the cords I5 and cause wicking.

After the lap seam Ill has been formed as above described and as shown in Fig. 3, and the tank has been vulcanized on the form i l, all that remains is to remove this tank from the formy II' and turn the tank inside out so that the liquid tight lap seam i' which is shown at the outer face of the tank in Fig. 1 will now lie at the inner face of the tank as shown in Fig. 4.

The lap seam formed in accordance with the present invention is strong, tight and easy to make and it is far more secure against leaks than are the cord fabric lap seams employed heretofore in the construction of flexible tanks and containers.

This invention mayv be used advantageously Where the cords are coated with natural rubber or other materials such as Buna N. Such Buna N coated cords are employed where the container is required to hold gasoline, xylene, benzine, etc. For other applications it may be desirable to use CTR-S or Neoprene or certain resin coated compositions, like polyvinyl chloride. If the coating is lacking in raw tack, it is necessary to use a suitable adhesive to join the overlapping edges of the coated cord.

Although the invention has been above described in connection with liquid containers, it may well be used in other applications where it is desired to join the overlapping marginal portions of coated cord fabric to form a liquid tight lap seam.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

l. A flexible liquid tight container made of coated cord fabric, and having a coated cord fabric lining provided with a leak-proof lap seam extending parallel to the cords of the lining. said seam being formed of two overlapping marginal portions of the lining so that one covers the other at the inner face of the container, the covering marginal portion adjacent its edge having a thin integral lip of the coating that is free of cord and said lip being bonded tothe underlying layer of cord fabric so as to form a tight seal over any cord at the base of such lip.

2. n-the manufacture of non-metallic liquid containers, the method of `ioining two marginal wall portions of coated cord fabric so as to form a tight lap sea-m at the inner wall of the container and extending parallel to thev cords of the fabric, which comprises overlapping two marginal portions of the coated cord fabric so that one marginal portionl covers the other at the inner Wall of the container, removing at least one cord'from the covering marginal portion adjacent its edge so as to leave a thin cord-free lip of the coating at this edge, and bonding this cord-free lip to the underlying layer of cord fabric so as to form a tight seal over any cord at the base of such lip.

MARION M. CUNNINGHAM.

REFERENCES CITED The following references are of record in the fleof` this patent:

UNITED STATES PATENTS Number Name Date 1,261,118 Geisel Apr. 2, 1918 2,016,851 Brady Oct. 8, 1935 2,022,501 Cramer Nov. 26, 1935 2,061,375 Cramer Nov. 17, 1936 2,098,258 Rowe Nov. 9, 1937 2,106,875 Rowe Feb. l, 1938 2,182,169 Bierer Dec. 5, 1939 y2,401,825 Eger June 4, 1946 2,404,766 Hanson et al July 23, 1946 2,439,562 Cunningham Apr. 13, 1948 2,476,325 Rowe July 19, 1949 

